Currently, researches are being conducted to provide various types of services such as multimedia services and to transmit a higher quality of data at higher rate in a wireless communication environment. Accordingly, technology associated with multiple input multiple output (MIMO) communication systems using multiple channels are in rapid development.
In a MIMO communication system, a base station may use a spatial division multiplexing (SDM) scheme and a spatial division multiplexing access (SDMA) scheme. For example, the base station may simultaneously transmit a plurality of data streams via a plurality of antennas according to the SDM scheme, and may transmit the plurality of data streams to multiple users via the plurality of antennas according to the SDMA scheme.
To effectively transmit the plurality of data streams using the plurality of antennas, the base station may need to verify channel information associated with downlink channels formed between the plurality of antennas and users. Accordingly, the users may feed back, to the base station, channel information associated with the downlink channels. The base station may configure a precoding matrix for the users based on the channel information. In this instance, the base station may perform beamforming of the data streams based on a plurality of precoding vectors included in a precoding matrix.
The plurality of precoding vectors may act as interference with respect to each other. The base station may feedforward, to a specific user, an indicator with respect to a precoding vector for the specific user and an indicator with respect to a remaining precoding vector. For example, when active users correspond to user A and user B, and a rank is two, it may be assumed that X denotes a precoding vector for the user A and Y denotes a precoding vector for the user B. In this case, the base station may inform the user A about that the precoding vector is X and an interference vector is Y, and may also inform the user B about that the precoding vector is Y and the interference vector is X.
The above feedforward processing may increase overhead in a communication system and thus there is a desire for technology that may effectively perform a feedforward process.